H.264 video compression standard provides two distinctive entropy coding methods to encode syntax elements, namely, Content Adaptive Binary Arithmetic Coding (CABAC, hereafter) and Content Adaptive Variable Length Coding (CAVLC, hereafter). It has been verified that CABAC generally provides superior coding efficiency over CAVLC due to its better content adaptive nature.
However, CABAC has a heavily sequential algorithm structure rendering it difficult to implement in a parallel fashion. Therefore, the total number of clocks required for encoding syntax elements (“SE”) for a single block unit (a “macroblock”) or a single slice can fluctuate wildly depending on the nature of raw video sequence and are therefore difficult to maintain within a well-defined limit.
The above properties of CABAC not only necessitate an ultra-fast processor for a real-time encoding on PC/DSP platforms, but also become a major obstacle for low-power implementation of H.264 on ASIC which is critical for consumer electronics applications. The present invention presented herein overcomes such obstacle by presenting novel methods for utilizing encoding methods in an efficient manner.
Note that the terminologies used herein may also be found and further specified in the H.264 documentation (JVT-N050d1).